1. Field of the Invention
The invention relates to the field of hearing devices, such as hearing aids and active hearing protection devices, and more particularly to an antenna module for hearing devices capable of receiving and/or transmitting electromagnetic signals. Furthermore, the invention relates to an ear tip comprising such an antenna module, and a hearing device comprising the same.
2. Description of the Related Art
Modern hearing devices have become extremely small, particularly in the case of ITE, CRT and CIC-type devices, and often incorporate a plurality of functionalities. For instance, it has become increasingly common for a wireless link to be incorporated in hearing devices, for various purposes such as receiving information, e.g. as electromagnetically encoded sound information from an induction loop; wireless programming of the hearing device; or for establishing a wireless link between two hearing devices, or between one or more hearing devices and a further device.
Conventionally, the antenna is a simple coil antenna wound around a simple cylindrical core made of a highly magnetically permeable material such as ferrite, and incorporated in any convenient position in the hearing device. This presents the disadvantages of taking up significant amounts of space in the hearing device and presenting significant design difficulties. In addition, the coil is often subject to parasitic electromagnetic fields emanating from electrical components in the hearing device, particularly from the receiver. As a result, shielding and/or compensation coils are required, which are bulky and take up a significant amount of space in the hearing device, to eliminate the negative effects of these parasitic electromagnetic fields.
The first of these disadvantages is at least partially overcome in EP 1 389 891 A2 by winding the antenna coil around an existing electro-acoustic transducer in the hearing aid device or around a capsule surrounding the transducer. While this saves space in the hearing device and allows increasing of the diameter of the antenna coil, this arrangement is also subject to undesired electromagnetic interference from the electromagnetic components, particularly those contained within the volume delimited by the antenna coils. As a result, shielding and/or compensation coils are still required. Furthermore, this arrangement prohibits the use of a magnetically permeable core, limiting the gain of the antenna.
The object of the present invention is therefore to overcome at least one of the above-mentioned disadvantages in the prior art, and thereby to provide an antenna module capable of high gain and with a minimised requirement for shielding and/or compensation.